with \(g_{1}=\frac{0.0738\left(\Omega _{b} h^{2}\right)^{-0.238}}{1+39.5\left(\Omega _{b} h^{2}\right)^{0.763}}\)  and \(g_{2}=\frac{0.560}{1+21.1\left(\Omega _{b} h^{2}\right)^{1.81}}\)  [1]}. \(r_s\)  is the comoving sound horizon, which is defined as
\(r_{s}(z)=\frac{1}{H_{0}} \int _{0}^{1 /(1+z)} \frac{d a}{a^{2} E(a) \sqrt{3\left(1+\frac{3 \Omega _{b} h^{2}}{4 \Omega _{\gamma } h^{2}} a\right)}},\) 
